/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.util.log;

import org.apache.juli.logging.Log;

/**
 * This helper class assists with the logging associated with invalid input
 * data. A developer may want all instances of invalid input data logged to
 * assist with debugging whereas in production it is likely to be desirable not
 * to log anything for invalid data. The following settings may be used:
 * <ul>
 * <li>NOTHING: Log nothing.</li>
 * <li>DEBUG_ALL: Log all problems at DEBUG log level.</li>
 * <li>INFO_THEN_DEBUG: Log first problem at INFO log level and any further
 * issues in the following TBD (configurable) seconds at DEBUG level</li>
 * <li>INFO_ALL: Log all problems at INFO log level.</li>
 * </ul>
 * By default, INFO_THEN_DEBUG is used with a suppression time of 24 hours.
 * <p>
 * NOTE: This class is not completely thread-safe. When using INFO_THEN_DEBUG it
 * is possible that several INFO messages will be logged before dropping to
 * DEBUG.
 */
public class UserDataHelper {

	private final Log log;

	private final Config config;

	// A value of 0 is equivalent to using INFO_ALL
	// A negative value will trigger infinite suppression
	// The value is milliseconds
	private final long suppressionTime;

	private volatile long lastInfoTime = 0;

	public UserDataHelper(Log log) {
		this.log = log;

		Config tempConfig;
		String configString = System.getProperty(
				"org.apache.juli.logging.UserDataHelper.CONFIG");
		if (configString == null) {
			tempConfig = Config.INFO_THEN_DEBUG;
		} else {
			try {
				tempConfig = Config.valueOf(configString);
			} catch (IllegalArgumentException iae) {
				// Ignore - use default
				tempConfig = Config.INFO_THEN_DEBUG;
			}
		}

		// Default suppression time of 1 day.
		suppressionTime = Integer.getInteger(
				"org.apache.juli.logging.UserDataHelper.SUPPRESSION_TIME",
				60 * 60 * 24).intValue() * 1000L;

		if (suppressionTime == 0) {
			tempConfig = Config.INFO_ALL;
		}

		config = tempConfig;
	}

	/**
	 * Returns log mode for the next log message, or <code>null</code> if the
	 * message should not be logged.
	 * <p>
	 * <p>
	 * If <code>INFO_THEN_DEBUG</code> configuration option is enabled, this
	 * method might change internal state of this object.
	 *
	 * @return Log mode, or <code>null</code>
	 */
	public Mode getNextMode() {
		if (Config.NONE == config) {
			return null;
		} else if (Config.DEBUG_ALL == config) {
			return log.isDebugEnabled() ? Mode.DEBUG : null;
		} else if (Config.INFO_THEN_DEBUG == config) {
			if (logAtInfo()) {
				return log.isInfoEnabled() ? Mode.INFO_THEN_DEBUG : null;
			} else {
				return log.isDebugEnabled() ? Mode.DEBUG : null;
			}
		} else if (Config.INFO_ALL == config) {
			return log.isInfoEnabled() ? Mode.INFO : null;
		}
		// Should never happen
		return null;
	}

	/*
	 * Not completely thread-safe but good enough for this use case. I couldn't
	 * see a simple enough way to make it completely thread-safe that was not
	 * likely to compromise performance.
	 */
	private boolean logAtInfo() {

		if (suppressionTime < 0 && lastInfoTime > 0) {
			return false;
		}

		long now = System.currentTimeMillis();

		if (lastInfoTime + suppressionTime > now) {
			return false;
		}

		lastInfoTime = now;
		return true;
	}

	private static enum Config {
		NONE,
		DEBUG_ALL,
		INFO_THEN_DEBUG,
		INFO_ALL
	}

	/**
	 * Log mode for the next log message.
	 */
	public static enum Mode {
		DEBUG(false), INFO_THEN_DEBUG(true), INFO(false);

		private final boolean fallToDebug;

		Mode(boolean fallToDebug) {
			this.fallToDebug = fallToDebug;
		}

		/**
		 * @deprecated Unused, removed in Tomcat 8.
		 */
		@Deprecated
		public boolean fallToDebug() {
			return fallToDebug;
		}
	}
}
